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"Martinez, P"
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GLOBAL CARLEMAN ESTIMATES FOR DEGENERATE PARABOLIC OPERATORS WITH APPLICATIONS
Degenerate parabolic operators have received increasing attention in recent years because they are associated with both important
theoretical analysis, such as stochastic diffusion processes, and interesting applications to engineering, physics, biology, and
economics.
This manuscript has been conceived to introduce the reader to global Carleman estimates for a class of parabolic
operators which may degenerate at the boundary of the space domain, in the normal direction to the boundary. Such a kind of degeneracy
is relevant to study the invariance of a domain with respect to a given stochastic diffusion flow, and appears naturally in climatology
models.
Global Carleman estimates are a priori estimates in weighted Sobolev norms for solutions of linear partial differential
equations subject to boundary conditions. Such estimates proved to be extremely useful for several kinds of uniformly parabolic
equations and systems. This is the first work where such estimates are derived for degenerate parabolic operators in dimension higher
than one. Applications to null controllability with locally distributed controls and inverse source problems are also developed in full
detail.
Compared to nondegenerate parabolic problems, the current context requires major technical adaptations and a frequent use
of Hardy type inequalities. On the other hand, the treatment is essentially self-contained, and only calls upon standard results in
Lebesgue measure theory, functional analysis and ordinary differential equations.
eBook
Plant compartment and biogeography affect microbiome composition in cultivated and native Agave species
Desert plants are hypothesized to survive the environmental stress inherent to these regions in part thanks to symbioses with microorganisms, and yet these microbial species, the communities they form, and the forces that influence them are poorly understood. Here we report the first comprehensive investigation of the microbial communities associated with species of Agave, which are native to semiarid and arid regions of Central and North America and are emerging as biofuel feedstocks. We examined prokaryotic and fungal communities in the rhizosphere, phyllosphere, leaf and root endosphere, as well as proximal and distal soil samples from cultivated and native agaves, through Illumina amplicon sequencing. Phylogenetic profiling revealed that the composition of prokaryotic communities was primarily determined by the plant compartment, whereas the composition of fungal communities was mainly influenced by the biogeography of the host species. Cultivated A. tequilana exhibited lower levels of prokaryotic diversity compared with native agaves, although no differences in microbial diversity were found in the endosphere. Agaves shared core prokaryotic and fungal taxa known to promote plant growth and confer tolerance to abiotic stress, which suggests common principles underpinning Agave–microbe interactions.
Journal Article
Phagocytosis in cellular defense and nutrition: a food-centered approach to the evolution of macrophages
The uptake of macromolecules and larger energy-rich particles into the cell is known as phagocytosis. Phagocytosed material is enzymatically degraded in membrane-bound vesicles of the endosome/lysosome system (intracellular digestion). Whereas most, if not all, cells of the animal body are equipped with the molecular apparatus for phagocytosis and intracellular digestion, a few cell types are specialized for a highly efficient mode of phagocytosis. These are the (“professional”) macrophages, motile cells that seek out and eliminate pathogenic invaders or damaged cells. Macrophages form the backbone of the innate immune system. Developmentally, they derive from specialized compartments within the embryonic mesoderm and early vasculature as part of the process of hematopoiesis. Intensive research has revealed in detail molecular and cellular mechanisms of phagocytosis and intracellular digestion in macrophages. In contrast, little is known about a second type of cell that is “professionally” involved in phagocytosis, namely the “enteric phagocyte.” Next to secretory (zymogenic) cells, enteric phagocytes form one of the two major cell types of the intestine of most invertebrate animals. Unlike vertebrates, these invertebrates only partially digest food material in the intestinal lumen. The resulting food particles are absorbed by phagocytosis or pinocytosis and digested intracellularly. In this review, we provide a brief overview of the enteric phagocytes described electron microscopically for diverse invertebrate clades, to then to compare these cells with the “canonical” phagocyte ultrastructure established for macrophages. In addition, we will review observations and speculations associated with the hypothesis that macrophages are evolutionarily derived from enteric phagocytes. This idea was already proposed in the late nineteenth century by Elias Metschnikoff who pioneered the research of phagocytosis for both macrophages and enteric phagocytes. We presume that modern approaches to better understand phagocytosis will be helped by considering the deep evolutionary relationship between the two cell types.
Journal Article
Psychological characteristics associated with COVID-19 vaccine hesitancy and resistance in Ireland and the United Kingdom
Identifying and understanding COVID-19 vaccine hesitancy within distinct populations may aid future public health messaging. Using nationally representative data from the general adult populations of Ireland (
N
= 1041) and the United Kingdom (UK;
N
= 2025), we found that vaccine hesitancy/resistance was evident for 35% and 31% of these populations respectively. Vaccine hesitant/resistant respondents in Ireland and the UK differed on a number of sociodemographic and health-related variables but were similar across a broad array of psychological constructs. In both populations, those resistant to a COVID-19 vaccine were less likely to obtain information about the pandemic from traditional and authoritative sources and had similar levels of mistrust in these sources compared to vaccine accepting respondents. Given the geographical proximity and socio-economic similarity of the populations studied, it is not possible to generalize findings to other populations, however, the methodology employed here may be useful to those wishing to understand COVID-19 vaccine hesitancy elsewhere.
Hesitancy and resistance towards vaccination is a challenge for public health. Here the authors determine psychological characteristics associated with COVID-19 vaccine hesitancy or resistance attitudes in the UK and Ireland.
Journal Article
2020 global reassessment of the neutrino oscillation picture
A
bstract
We present an updated global fit of neutrino oscillation data in the simplest three-neutrino framework. In the present study we include up-to-date analyses from a number of experiments. Concerning the atmospheric and solar sectors, besides the data considered previously, we give updated analyses of IceCube DeepCore and Sudbury Neutrino Observatory data, respectively. We have also included the latest electron antineutrino data collected by the Daya Bay and RENO reactor experiments, and the long-baseline T2K and NO
ν
A measurements, as reported in the Neutrino 2020 conference. All in all, these new analyses result in more accurate measurements of
θ
13
,
θ
12
,
Δ
m
21
2
and
Δ
m
31
2
. The best fit value for the atmospheric angle
θ
23
lies in the second octant, but first octant solutions remain allowed at ∼ 2
.
4
σ
. Regarding CP violation measurements, the preferred value of
δ
we obtain is 1.08
π
(1.58
π
) for normal (inverted) neutrino mass ordering. The global analysis still prefers normal neutrino mass ordering with 2.5
σ
statistical significance. This preference is milder than the one found in previous global analyses. These new results should be regarded as robust due to the agreement found between our Bayesian and frequentist approaches. Taking into account only oscillation data, there is a weak/moderate preference for the normal neutrino mass ordering of 2
.
00
σ
. While adding neutrinoless double beta decay from the latest Gerda, CUORE and KamLAND-Zen results barely modifies this picture, cosmological measurements raise the preference to 2
.
68
σ
within a conservative approach. A more aggressive data set combination of cosmological observations leads to a similar preference for normal with respect to inverted mass ordering, namely 2
.
70
σ
. This very same cosmological data set provides 2
σ
upper limits on the total neutrino mass corresponding to Σ
m
ν
<
0
.
12 (0
.
15) eV in the normal (inverted) neutrino mass ordering scenario. The bounds on the neutrino mixing parameters and masses presented in this up-to-date global fit analysis include all currently available neutrino physics inputs.
Journal Article
Pandemic buying: Testing a psychological model of over-purchasing and panic buying using data from the United Kingdom and the Republic of Ireland during the early phase of the COVID-19 pandemic
The over-purchasing and hoarding of necessities is a common response to crises, especially in developed economies where there is normally an expectation of plentiful supply. This behaviour was observed internationally during the early stages of the Covid-19 pandemic. In the absence of actual scarcity, this behaviour can be described as ‘panic buying’ and can lead to temporary shortages. However, there have been few psychological studies of this phenomenon. Here we propose a psychological model of over-purchasing informed by animal foraging theory and make predictions about variables that predict over-purchasing by either exacerbating or mitigating the anticipation of future scarcity. These variables include additional scarcity cues (e.g. loss of income), distress (e.g. depression), psychological factors that draw attention to these cues (e.g. neuroticism) or to reassuring messages (eg. analytical reasoning) or which facilitate over-purchasing (e.g. income). We tested our model in parallel nationally representative internet surveys of the adult general population conducted in the United Kingdom (UK: N = 2025) and the Republic of Ireland (RoI: N = 1041) 52 and 31 days after the first confirmed cases of COVID-19 were detected in the UK and RoI, respectively. About three quarters of participants reported minimal over-purchasing. There was more over-purchasing in RoI vs UK and in urban vs rural areas. When over-purchasing occurred, in both countries it was observed across a wide range of product categories and was accounted for by a single latent factor. It was positively predicted by household income, the presence of children at home, psychological distress (depression, death anxiety), threat sensitivity (right wing authoritarianism) and mistrust of others (paranoia). Analytic reasoning ability had an inhibitory effect. Predictor variables accounted for 36% and 34% of the variance in over-purchasing in the UK and RoI respectively. With some caveats, the data supported our model and points to strategies to mitigate over-purchasing in future crises.
Journal Article
Doublons, topology and interactions in a one-dimensional lattice
We investigate theoretically the Bose–Hubbard version of the celebrated Su-Schrieffer-Heeger topological model, which essentially describes a one-dimensional dimerized array of coupled oscillators with on-site interactions. We study the physics arising from the whole gamut of possible dimerizations of the chain, including both the weakly and the strongly dimerized limiting cases. Focusing on two-excitation subspace, we systematically uncover and characterize the different types of states which may emerge due to the competition between the inter-oscillator couplings, the intrinsic topology of the lattice, and the strength of the on-site interactions. In particular, we discuss the formation of scattering bands full of extended states, bound bands full of two-particle pairs (including so-called ‘doublons’, when the pair occupies the same lattice site), and different flavors of topological edge states. The features we describe may be realized in a plethora of systems, including nanoscale architectures such as photonic cavities, optical lattices and qubits, and provide perspectives for topological two-particle and many-body physics.
Journal Article
The neglected role of relative humidity in the interannual variability of urban malaria in Indian cities
The rapid pace of urbanization makes it imperative that we better understand the influence of climate forcing on urban malaria transmission. Despite extensive study of temperature effects in vector-borne infections in general, consideration of relative humidity remains limited. With process-based dynamical models informed by almost two decades of monthly surveillance data, we address the role of relative humidity in the interannual variability of epidemic malaria in two semi-arid cities of India. We show a strong and significant effect of humidity during the pre-transmission season on malaria burden in coastal Surat and more arid inland Ahmedabad. Simulations of the climate-driven transmission model with the MLE (Maximum Likelihood Estimates) of the parameters retrospectively capture the observed variability of disease incidence, and also prospectively predict that of ‘out-of-fit’ cases in more recent years, with high accuracy. Our findings indicate that relative humidity is a critical factor in the spread of urban malaria and potentially other vector-borne epidemics, and that climate change and lack of hydrological planning in cities might jeopardize malaria elimination efforts.
Climate conditions and urbanization can be major drivers of vector-borne infections. Here the authors demonstrate that an often-neglected climate variable, humidity, is an important factor for malaria epidemics in two urban areas in India.
Journal Article
Staged developmental mapping and X chromosome transcriptional dynamics during mouse spermatogenesis
Male gametes are generated through a specialised differentiation pathway involving a series of developmental transitions that are poorly characterised at the molecular level. Here, we use droplet-based single-cell RNA-Sequencing to profile spermatogenesis in adult animals and at multiple stages during juvenile development. By exploiting the first wave of sperma- togenesis, we both precisely stage germ cell development and enrich for rare somatic cell- types and spermatogonia. To capture the full complexity of spermatogenesis including cells that have low transcriptional activity, we apply a statistical tool that identifies previously uncharacterised populations of leptotene and zygotene spermatocytes. Focusing on post- meiotic events, we characterise the temporal dynamics of X chromosome re-activation and profile the associated chromatin state using CUT&RUN. This identifies a set of genes strongly repressed by H3K9me3 in spermatocytes, which then undergo extensive chromatin remo- delling post-meiosis, thus acquiring an active chromatin state and spermatid-specific expression.
Journal Article